Antenna mountable in small spaces



Nov. 10, 1953 A. DORNE ETAL Filed April 50, 1946 FlG.l

FIG. 3

iNVENTORS DAVID LAZARUS HERBERT R MINOT ATTORNEY Patented Nov. 10, 1953 ANTENNA MOUNTABLE IN SMALL SPACES Arthur Dorne, Mineola,

Chicago, Ill., and Herb Mass, assignors to the ma as represented by the Secretary of War Application April 30, 1946, Serial No. 665,990

Claims.

This invention relates to electrical apparatus and more particularly to improvements in antennas.

In the design of antennas for aircraft installations, it is desired to minimize wind resistance. Previous antenna designs have in general required a substantially hemispherical radiating aperture. Streamlined antenna stubs (one-half of a dipole above a reflecting plane) and various specal antennas generally mounted within a blister (hemispherical projection) on the aircraft have been used. Such designs usually cannot be mounted within the confines of the aircraft surfaces and require some external projection on the surface of the aircraft. This difficulty is associated principally with the large radiating aperture required.

An ob ect of the present invention is to provide an antenna system having a relatively small radiating aperture and adapted to be mounted within th confines of a curved metallic surface.

A further object of the present invention is to provide such an antenna system with fairly broad radiation patterns in both horizontal and vertical planes.

A further object of the present invention is to effectively match said antenna system to its feed line.

Other objects and advantages of the invention will be apparent during the course of the following description.

The present invention may best be classified as a radiator of high frequency electromagnetic energy. It is constructed as a fairly short section of parallel plate transmission line which is shortcircuited at one end. Disposed within the waveguide space of this transmission line is an antenna stub. The term stub denotes a radiating element having an effective electrical length of a quarter wavelength'or less and mounted above a reflecting plane. This antenna stub is capacitively loaded in order to increase its electrical length and to more closed match its radiation resistance to the characteristic impedance of its feed line. By means of this capacitive loading, the overall size of the antenna system is greatly reduced. The parallel plate transmission line may be shaped to conform with the outline of a curved surface such as the leading edge of thewing-or the wing tip of an airplane, and the entire antenna system may be completely inclosed within the confines of the aircraft wing surface is such a manner as to not disturb the streamlined surface of that member.

In the accompanying drawing forming a part of this'specification Fig. 1 is a broken-away isometric view of one embodiment of the present invention;

Fig. 1(a) is a simplified top view of Fig. 1, drawn to a reduced scale; 7

- Fig. 2 is a simplified top View of another em- N. Y., David Lazarus, ert P. Minot, Belmont, United States of Amerbodiment of the present invention which utilizes a slightly different form of capacitive loading; and

Fig. 3 is a simplified to view of a third embodiment of the present invention which utilizes still another method of capacitive loading.

In Fi 1. wherein is shown one poss ble embodiment of the resent invent on. numerals I l and I I desi nate two substantially parallel con ucting p ates which in e ect form a sect on of arallel plate transmission line. A conductin ha k p ate I2 is disposed substantially perpendicu arly to parallel plates I l and II and terminates the transm ssion l ne f rmed by pl tes III and II at one end thereof. The ed es of plates Ill and. II may be sha ed to co form to a curve s rf ce such as the leadin e ge of the wing or the ateral wing t p of an aircraft. D ose w th n the waveguide space formed by ates I". I I and I! is a conical antenna stub I3 (hest s n in Fi 1(a)) having a capacitive loa n element I4. Capa itive loadin eleme t I A s h sh wn as a U-sha ed stove pi e member but other cana d.- tive loading means may be used if desired. he ca citive lo ding element I4 s su ported. maintained ri idlv with respect to the plates by means of insulating su ports I5 w ch ext nd between end closure plates on c pac t ve loading element I4 and the back plate I2. The antenna stub I3 is fed by a coaxial line I6 having its inner conductor I'I electrically connected to stub I 3 and its outer conductor I8 electrically connected to conducting plate III.

Fig. 1(a) shows a sim lified top view of Fig. 1 drawn to a reduced scale, and is included to more clearly illustrate the use of alternate ty es of antenna stubs and capacitive loading means. In Fig. 2 a cone antenna I9 re laces the antenna, stub I3 and ca acitive loading element I4 of Fig. 1(a). cal antenna stub I3 is utilized instead of antenna stub I3 of Fig. 1(a). The capacitive loading is effected by a conducting plate I 4'.

The waveguide formed by plates III, II and I2 is the actual radiator of electromagnetic ener y.- Electromagnetic waves may be set u in this waveguide space by a capacity-loaded antennastub; This exciting antenna may be the conical antenna stub I3 and capacitive loading element I4, the cone antenna I9, or the conical antenna stub I3, and capacitive loading plate I 4'. The capacitive loading serves to increase the electrical lengths of the antenna stub and to more effectively match it to the coaxial line IS. The polarization of the radiated electromagnetic energy is parallel to the axis of the antenna stub (i. e. to the axis of the cone) and the parallel plates I 0 and I I propagate electromagnetic energy therebetween in the transmission line mode. These radiators are fairly broad-band and the In Fig. 3 a somewhat enlarged c0ni-.

radiation, patterns are. broad and. symmetrical in both horizontal and vertical planes.

Such an antenna system may readily be built within the confines of a curved surface having: a radius of the order of an eighth wavelength. Because of its shape and small size, it mayreact ily be placed within the leading edge oithe wing or the lateral wing tip of an. aircraft, where other types of antennas would notv bepractical. The choice between the two locations would in: general be determined by the desired polarization of the emitted radiation. The polarization will be parallel to the axis of the conical stubs. For horizontal polarization theantenna system would generally be: mounted. within the leading, edge of the aircraft wing. with. the curved edges. of plates HT and' N conforming to the curved surface of the leading edge. For vertical polarization the antenna system would generally be turned on its side and mounted in the wing, tip of. the aircraft; However, in the majority of applications the antenna system may be" mounted in the position" shown or; turned on its side in either the leading edge of the: aircraft. wing or inthewing tip, allowing the attainment of the desired direction of polarization in either location.

While the present invention has been described emphasizing its particular applicability for aircraft installation, the invention is not limited thereto, and maybe applied as well in other install'ations which permit its use.

It will be apparent that there may be deviations from the invention as described which still fall fairly within the spirit and scope of the invention.

What is claimed is:

1. A radiator of high frequency electromagnetic energy including two conducting plates lying wholly in substantially parallel planes, a third conducting'pl'ate disposed substantially perpendicularly to and connecting said parallel plates at one end thereof, said parallel plates being insulated from one another except for the connection of said third plate, said plates defining therebetween a transmission line, a conical antenna stub disposed within said transmission line and having its axissubstantially perpendicular to said parallel plates, said antenna stub having a length less than a quarter the length of the operating wave, capacitive loading means being electrically connected to said antenna stub for increasing the electrical length thereof, and a coaxial line external to said transmission line, the center conductor of said coaxial line being electrically connected to said antenna stub and the outer conductor being electrically connected to said conducting plates.

2. A radiator of high frequency electromagnetic energy including two conducting plates lying wholly in substantially parallel planes, a third conducting plate disposedsubstantially perpendieularly to. and. connecting said parallel plates at one. end thereof, said parallel plates. being insulated from one another except for the connection of said third plate, said plates defining. therebetween a transmission. line, a 001182119- tenna disposed within-said transmission line, and a coaxial line: external to said transmission line extending through; oneof said parallel lates andhaving its inner conductor electrically connected to said cone antenna and its outer conductor electrically connected to said one: parallel plate.

3; A high. frequency radiator adaptedfor '4 mounting; in a small space; comprising a pair of plates. lying; wholly in. substantially parallel planes to form a transmission line, a conducting plate mounted perpendicular to said parallel plates and short-circuiting said parallel plates at oneend, said parallel plates being insulated from one. another. except for the connection of said; perpendicular plate, said plates being shaped at the-end remotefrom said one end to fit in the space. in. which said radiator is to be mounted, a conical stub antenna mounted in the space between said parallel plates and oriented to feed high. frequency energy to said parallel plates in the transmission line mode, a coaxial line extending, through one of. said parallel plates and having, anouter conductor connected to said one .parallel plate and an inner conductorconnect'ed to said. antenna for feeding the high frequency energy. thereto,.and a conductor connected to said antenna and capacitivel'y coupled to said parallel plates for increasing the electricallength of said antenna.

4. A high frequency radiator'comprising asection of. transmission line composed of two conductive plates lying wholly in substantially parallel planes, said transmission line being shortcircuited at one end by another conductive plate lying wholly in a plane perpendicular to saidconductive plates and opened on all other sides, means coupled to said line for feeding high frequency electromagnetic energy thereto in the transmission line mode, said feeding means including a radiating conductor mounted in the space between said parallel plates of said transmission line. and means capacitatively coupling said. radiating conductor and said. transmission line.

5. A high frequency radiator comprising three conductive plates, two of said plates lying wholly in. substantially parallel planes, the third one of said plates being mounted transversely to said parallel plates and lying wholly ina plane substantially perpendicular thereto and short-circuiti'ng said parallel plates at one end thereof, said parallel plates being insulated from one another except at said short-circuited end and forming a transmission line open circuited at the end remote from said one end for radiating energy from said remote end, means coupled to said transmission lineforfeeding high frequency electromagnetic energy thereto in. the transmission line mode, said feeding means comprising a conical radiating conductor oriented in the space between said parallel plates to feed said plates with high frequency electromagnetic energy inthe transmission line mode, and an additional conductor connected to said radiating conductor and capacitatively coupled to said parallel plates for increasing the effective electrical length of said electrical conductor.

ARTHUR DORNE. DAVID LAZARUS. HERBERT P. MINOT.

References Cited in the tile of this patent UNITED STATES PATENTS Number: Name Date 2,218,741 Buschbeck Oct. 22, 1940 2,253,501 Barrow Aug; 26, 1941 2,255,042 Barrow Sept. 9, 1941 2,275,646 Peterson Mar. 10, 1942 2,368,663 Kandoian Feb. 6, 1945 2,423,150 Lindenblad July 1, 1947 2,433,368 Johnson et'al. Dec. 30, 1947 2,539,680 Wehner Jan130, 1951 

